Atherosclerotic vascular disease represents one of the major health problems in the world. It is the number one cause of death in the United States, being responsible for one third of all reported mortality on an annual basis. The magnitude of the problem is staggering; in the United States alone over 60 million people have some form of atherosclerotic vascular disease. In 1995, approximately 1,000,000 people died from this problem. Atherosclerotic vascular disease ranks as the leading reason for social security disability, limitation in physical activity, and hospital bed use accounting for 46 million bed days in 1994. The direct and indirect costs of treating this scourge is in the hundreds of billions of dollars on an annual basis.
Although research in this area has been intense, the exact cause of atherosclerotic artery disease remains unknown. Atherosclerosis is the descriptive term for thickened and hardened lesions of the arteries. It results from fatty deposits that build up in the innermost lining, or intima, of the artery. The lesions are generally eccentric and if they become sufficiently large, can occlude the artery and thus the blood supply to a tissue or organ, resulting in ischemia or necrosis. If this occurs, it often leads to the characteristic clinical outcomes of myocardial infarction (heart attack), cerebral infarction (stroke), gangrene of the extremities, etc.
The exact cause of the fatty build-up is not known although the stages of progression are well described and certain risk factors well-identified, such as smoking, high cholesterol levels, obesity, diabetes etc. More recently, evidence has pointed to a potential infectious cause of atherosclerotic vascular disease. Cytomegalo virus, Chlamydia, Helicobacter pylori, and porphyromona gingivalis have all been associated with atherosclerotic disease. The infectious pathogens are presumed to cause chronic inflammation, which results in atherosclerotic deposition.
In one study involving Helicobacter pylori, 38 atherosclerotic plaques were obtained at carotid endarterctomy, and examined for the presence or absence of bacteria. The researchers used morphological and immunohistochemical techniques to do this, and a highly sensitive polymerase chain reaction method to search for Helicobacter DNA. As a control, the researchers examined 7 carotid arteries obtained at autopsy from subjects without carotid atherosclerosis. The researchers detected the presence of Helicobacter pylori DNA in 20 out of 38 atheromatous plaques, and morphological/immunohistochemical evidence of bacteria in 10 of the DNA-positive plaques. None of the 7 normal carotid arteries were positive for Helicobacter pylori (Ameriso, 2001).
If atherosclerotic artery disease were to be infectious in etiology, antibiotics probably would not work well due to lack of penetration into dense plaque.
Besides the possibility of an infectious etiology, atherosclerosis involves chronic inflammation of the vessels. It is now apparent that chronic systemic inflammatory or infectious conditions, such as chronic gum disease, can lead to up-regulation of inflammatory reactions or proteins such as C-reactive protein. Either the proximate cause of the inflammation, such as the bacteria Porphyromona gingivalis in chronic gum disease or the resulting release or up-regulation of the inflammatory condition can spread to the vessels, such as coronary arteries, and cause atherosclerosis without other injurious environmental factors, such as high cholesterol or smoking.
In view of these and other deficiencies of the prior art it is the primary object of the present invention to provide an apparatus and method for treating atherosclerotic vascular disease using light radiation.
Another more specific object is to treat vascular disease of the character described using light radiation without significant damage to the vessel or surrounding body tissue.
A further object of the present invention is to provide an apparatus of the type described which is characterized by emitting radiation which is destructive to pathogenic microorganisms that cause and/or contribute to atherosclerotic disease without producing sufficient heat to damage body tissues.
Yet another object of the invention is to provide an apparatus of the character described which is small enough for insertion into relatively small blood vessels such as the coronary arteries but is also useful for treating blood vessels throughout the body including cerebral vessels and peripheral vessels that are partially or completely occluded by atherosclerotic plaque.
A still further object of the present invention is the provision of a method and apparatus for treating vascular disease and especially coronary artery disease by reducing or eliminating bacterial infections in other parts of the body and especially the mouth.
These and other more detailed and specific objects of the present invention will be better understood by reference to the following figures and detailed description which illustrate by way of example of but a few of the various forms of the invention within the scope of the appended claims.